aocc23

Advent of Code 2023
git clone git://www.tkruger.se/aocc23.git
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uppga.c (2132B)

      1 #include "common.h"
      2 
      3 static inline int is_expandable_row(size_t i, char **lines, size_t ncols) {
      4   size_t j;
      5   for (j = 0; j < ncols; j++) {
      6     if (lines[i][j] != '.')
      7       return 0;
      8   }
      9   return 1;
     10 }
     11 
     12 static inline int is_expandable_col(size_t i, char **lines, size_t nrows) {
     13   size_t j;
     14   for (j = 0; j < nrows; j++) {
     15     if (lines[j][i] != '.')
     16       return 0;
     17   }
     18   return 1;
     19 }
     20 
     21 static inline int isin(size_t i, size_t *lst, size_t nlst) {
     22   size_t j;
     23   for (j = 0; j < nlst; j++) {
     24     if (lst[j] == i)
     25       return 1;
     26   }
     27 
     28   return 0;
     29 }
     30 
     31 static inline uint64_t count_betw(size_t ca, size_t cb, size_t *lst,
     32                                   size_t nlst) {
     33   size_t mi = ca > cb ? cb : ca;
     34   size_t ma = ca > cb ? ca : cb;
     35 
     36   uint64_t count = 0;
     37   size_t i;
     38   for (i = mi; i < ma; i++) {
     39     if (isin(i, lst, nlst)) {
     40       count += 2;
     41     } else {
     42       count++;
     43     }
     44   }
     45 
     46   return count;
     47 }
     48 
     49 int main(int argc, char **argv) {
     50   char **lines;
     51   size_t i, j;
     52   size_t nrows = readlines(&lines, "input");
     53   size_t ncols = strlen(lines[0]) - 1;
     54 
     55   size_t expand_cols[2 * ncols];
     56   size_t expand_rows[2 * nrows];
     57   size_t nexpand_cols = 0;
     58   size_t nexpand_rows = 0;
     59 
     60   for (i = 0; i < nrows; i++) {
     61     if (is_expandable_row(i, lines, ncols)) {
     62       expand_rows[nexpand_rows] = i;
     63       nexpand_rows++;
     64     }
     65   }
     66 
     67   for (i = 0; i < ncols; i++) {
     68     if (is_expandable_col(i, lines, nrows)) {
     69       expand_cols[nexpand_cols] = i;
     70       nexpand_cols++;
     71     }
     72   }
     73 
     74   size_t galaxies[4 * ncols * nrows][2];
     75   size_t ngalaxies = 0;
     76   for (i = 0; i < nrows; i++) {
     77     for (j = 0; j < ncols; j++) {
     78       if (lines[i][j] == '#') {
     79         galaxies[ngalaxies][0] = i;
     80         galaxies[ngalaxies][1] = j;
     81         ngalaxies++;
     82       }
     83     }
     84   }
     85 
     86   uint64_t summarum = 0;
     87   for (i = 0; i < ngalaxies - 1; i++) {
     88     for (j = i + 1; j < ngalaxies; j++) {
     89       uint64_t rowc =
     90           count_betw(galaxies[i][0], galaxies[j][0], expand_rows, nexpand_rows);
     91       uint64_t colc =
     92           count_betw(galaxies[i][1], galaxies[j][1], expand_cols, nexpand_cols);
     93       summarum += rowc + colc;
     94     }
     95   }
     96 
     97   printf("%llu\n", summarum);
     98 }